/Engine/Source/Editor/BlueprintEditorLibrary/Public/BlueprintEditorLibrary.h
Sets "Instance Editable" to true/false on a Blueprint variable
static void SetBlueprintVariableInstanceEditable ( [UBlueprint](API\Runtime\Engine\Engine\UBlueprint) * Blueprint, const [FName](API\Runtime\Core\UObject\FName) & VariableName, bool bInstanceEditable )